The invention relates to an apparatus for mixing two or more flowable materials to obtain a uniform mixture. Materials which may be mixed include liquids, gases, or finely divided solids. The invention relates in particular to a mixing apparatus having an elongated shape and provided internally with a plurality of baffles which interfere with and cause turbulence in the flow in the apparatus.
Mixing apparatus of the above type is widely applied for a great variety of purposes, such as the production of uniform mixtures of liquids, gases, and finely divided solids, and the production of compounds, such as, for example, resins from reactive liquids.
Upon flowing materials through such an apparatus, the baffles constitute obstructions in the flow, which obstructions cause turbulence in the flowing material, resulting in mixing of the various components in the flowing material. Dependent on the compositions of the materials, the result of flowing through the apparatus may be a uniform mixture, or it may be a compound if the components in the flow are reactive with one another.
Increase of the turbulence in the flow is, however, accompanied by an increase of the pressure drop over the mixing apparatus.
In the usual mixing apparatuses of the above type, the baffles are fixedly mounted in the passage for the flow, and may have various shapes, such as for example the shape of a spiral. These known mixing apparatus are sometimes called static mixers.
A consequence of the application of fixedly mounted baffles is a limitation on the range of applicability of a static mixer, as discussed below. It is this limitation that is avoided by the present invention.
At low flow velocities in a static mixer, of the usual sort, the resistance caused by the baffles will be rather low, so that turbulence of the flow (and therefore uniform mixing) will not readily occur, especially with rather viscous materials. On the other hand, at high flow velocities wherein the velocity itself generates turbulence in the flow, the baffles are not needed to contribute to the turbulence. Further, the resistance caused by the baffles as such high velocities easily becomes so great that the pressure drop over the mixing apparatus increases dramatically. Such a high pressure drop will cause a decrease of the pumping capacity of the supply pump(s) resulting in a lower capacity of the mixer.